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[SCEV] Rely on ConstantRange instead of custom logic; NFCI

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This was first landed in rL283058 and subsequenlty reverted since a
change this depends on (rL283057) was buggy and had to be reverted.

llvm-svn: 283079
This commit is contained in:
Sanjoy Das 2016-10-02 20:59:10 +00:00
parent c7d3291b68
commit 4aeb0f2c7f
1 changed files with 58 additions and 130 deletions
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188
llvm/lib/Analysis/ScalarEvolution.cpp
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@ -7337,149 +7337,77 @@ bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
// cases, and canonicalize *-or-equal comparisons to regular comparisons.
if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
const APInt &RA = RC->getAPInt();
switch (Pred) {
default: llvm_unreachable("Unexpected ICmpInst::Predicate value!");
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_NE:
// Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
if (!RA)
if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
if (const SCEVMulExpr *ME = dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
ME->getOperand(0)->isAllOnesValue()) {
RHS = AE->getOperand(1);
LHS = ME->getOperand(1);
Changed = true;
}
break;
case ICmpInst::ICMP_UGE:
if ((RA - 1).isMinValue()) {
Pred = ICmpInst::ICMP_NE;
bool SimplifiedByConstantRange = false;
if (!ICmpInst::isEquality(Pred)) {
ConstantRange ExactCR = ConstantRange::makeExactICmpRegion(Pred, RA);
if (ExactCR.isFullSet())
goto trivially_true;
else if (ExactCR.isEmptySet())
goto trivially_false;
APInt NewRHS;
CmpInst::Predicate NewPred;
if (ExactCR.getEquivalentICmp(NewPred, NewRHS) &&
ICmpInst::isEquality(NewPred)) {
// We were able to convert an inequality to an equality.
Pred = NewPred;
RHS = getConstant(NewRHS);
Changed = SimplifiedByConstantRange = true;
}
}
if (!SimplifiedByConstantRange) {
switch (Pred) {
default:
break;
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_NE:
// Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
if (!RA)
if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
if (const SCEVMulExpr *ME =
dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
ME->getOperand(0)->isAllOnesValue()) {
RHS = AE->getOperand(1);
LHS = ME->getOperand(1);
Changed = true;
}
break;
// The "Should have been caught earlier!" messages refer to the fact
// that the ExactCR.isFullSet() or ExactCR.isEmptySet() check above
// should have fired on the corresponding cases, and canonicalized the
// check to trivially_true or trivially_false.
case ICmpInst::ICMP_UGE:
assert(!RA.isMinValue() && "Should have been caught earlier!");
Pred = ICmpInst::ICMP_UGT;
RHS = getConstant(RA - 1);
Changed = true;
break;
}
if (RA.isMaxValue()) {
Pred = ICmpInst::ICMP_EQ;
Changed = true;
break;
}
if (RA.isMinValue()) goto trivially_true;
Pred = ICmpInst::ICMP_UGT;
RHS = getConstant(RA - 1);
Changed = true;
break;
case ICmpInst::ICMP_ULE:
if ((RA + 1).isMaxValue()) {
Pred = ICmpInst::ICMP_NE;
case ICmpInst::ICMP_ULE:
assert(!RA.isMaxValue() && "Should have been caught earlier!");
Pred = ICmpInst::ICMP_ULT;
RHS = getConstant(RA + 1);
Changed = true;
break;
}
if (RA.isMinValue()) {
Pred = ICmpInst::ICMP_EQ;
Changed = true;
break;
}
if (RA.isMaxValue()) goto trivially_true;
Pred = ICmpInst::ICMP_ULT;
RHS = getConstant(RA + 1);
Changed = true;
break;
case ICmpInst::ICMP_SGE:
if ((RA - 1).isMinSignedValue()) {
Pred = ICmpInst::ICMP_NE;
case ICmpInst::ICMP_SGE:
assert(!RA.isMinSignedValue() && "Should have been caught earlier!");
Pred = ICmpInst::ICMP_SGT;
RHS = getConstant(RA - 1);
Changed = true;
break;
}
if (RA.isMaxSignedValue()) {
Pred = ICmpInst::ICMP_EQ;
Changed = true;
break;
}
if (RA.isMinSignedValue()) goto trivially_true;
Pred = ICmpInst::ICMP_SGT;
RHS = getConstant(RA - 1);
Changed = true;
break;
case ICmpInst::ICMP_SLE:
if ((RA + 1).isMaxSignedValue()) {
Pred = ICmpInst::ICMP_NE;
case ICmpInst::ICMP_SLE:
assert(!RA.isMaxSignedValue() && "Should have been caught earlier!");
Pred = ICmpInst::ICMP_SLT;
RHS = getConstant(RA + 1);
Changed = true;
break;
}
if (RA.isMinSignedValue()) {
Pred = ICmpInst::ICMP_EQ;
Changed = true;
break;
}
if (RA.isMaxSignedValue()) goto trivially_true;
Pred = ICmpInst::ICMP_SLT;
RHS = getConstant(RA + 1);
Changed = true;
break;
case ICmpInst::ICMP_UGT:
if (RA.isMinValue()) {
Pred = ICmpInst::ICMP_NE;
Changed = true;
break;
}
if ((RA + 1).isMaxValue()) {
Pred = ICmpInst::ICMP_EQ;
RHS = getConstant(RA + 1);
Changed = true;
break;
}
if (RA.isMaxValue()) goto trivially_false;
break;
case ICmpInst::ICMP_ULT:
if (RA.isMaxValue()) {
Pred = ICmpInst::ICMP_NE;
Changed = true;
break;
}
if ((RA - 1).isMinValue()) {
Pred = ICmpInst::ICMP_EQ;
RHS = getConstant(RA - 1);
Changed = true;
break;
}
if (RA.isMinValue()) goto trivially_false;
break;
case ICmpInst::ICMP_SGT:
if (RA.isMinSignedValue()) {
Pred = ICmpInst::ICMP_NE;
Changed = true;
break;
}
if ((RA + 1).isMaxSignedValue()) {
Pred = ICmpInst::ICMP_EQ;
RHS = getConstant(RA + 1);
Changed = true;
break;
}
if (RA.isMaxSignedValue()) goto trivially_false;
break;
case ICmpInst::ICMP_SLT:
if (RA.isMaxSignedValue()) {
Pred = ICmpInst::ICMP_NE;
Changed = true;
break;
}
if ((RA - 1).isMinSignedValue()) {
Pred = ICmpInst::ICMP_EQ;
RHS = getConstant(RA - 1);
Changed = true;
break;
}
if (RA.isMinSignedValue()) goto trivially_false;
break;
}
}